Glove boxes and similar containments

ABSTRACT

A glove box or similar containment is provided with an extract system which includes a vortex amplifier venting into the system, the vortex amplifier also having its main inlet in fluid flow connection with the containment and a control inlet in fluid flow connection with the atmosphere outside the containment.

United States Patent Strong et al.

GLOVE BOXES AND SIMILAR CONTAINMENTS Inventors: Robert Edmund Strong, Lurbcrt;

Kenneth Boyle; John Grant. both of Warrington, all of England Assignees: British Nuclear Fuels Limited,

Riseley Warrington Cheshire; United Kingdom Atomic Energy Authority, London, both of England Filed: Nov. 30, 1973 Appl. No.1 420,585

Foreign Application Priority Data Dec. I1, 1972 United Kingdom............... 56987/72 US. Cl 312/1; l37/8l0 Int. Cl. Fl5c 1/16 Field of Search 137/561, 808, 809, 810,

137/811, 812, 813; 98/ll5 LH; 3l2/l June 10, 1975 [56] References Cited UNITED STATES PATENTS 3,324,89l 6/1967 Rhoades l. mm: 335L080 ll/l967 Datwylcr. Jr. et al. l37/Rl2 X 3.358.579 lZ/l967 Hauville 98/] I5 LH 3.4l0.6l9 ll/l968 Dclngy et al. 3lZ/l 3.424.182 lll969 Mayer l37/8l2 3.674.044 7/l972 Mayer .v l37/8l2 Primary E.raminerWilliam R. Cline Attorney Agent. or Firm-Larson, Taylor and Hinds 5 7 ABSTRACT A glove box or similar containment is provided with an extract system which includes a vortex amplifier venting into the system, the vortex amplifier also having its main inlet in fluid flow connection with the containment and a control inlet in fluid flow connection with the atmosphere outside the containment.

4 Claims, 1 Drawing Figure GLOVE BOXES AND SIMILAR CONTAINMENTS This invention relates to glow boxes and similar containments.

SUMMARY OF THE INVENTION According to the present invention a glove box or similar containment is provided with an extract system including a vortex amplifier venting into the system. the vortex amplifier also having its main inlet in lluid flow connection with the containment and a control inlet in fluid flow connection with the atmosphere outside the containment.

Glove boxes are a form of protection used when working with certain radioactive or toxic materials. Gloves fixed to ports in the wall ofa box allow a human operator to manipulate work within the box. Inhalation of fine airborne particles of poisonous alpha-active or other materials by the operator is avoided by maintaining the glove box atmosphere at a slight under pressure so that any air flow is inwards. There is also generally provided an air inlet for the glove box and an extract system which is typically a duct including a fan, a filter, and a diaphragm valve set manually to give the required glove box depression. say l /2 inch WG. [f a breach in containment occurs due to a glove becoming detached from a glove port, then the diaphragm valve has to be opened manually to draw more air through the glove box and thus prevent back diffusion of the glove box air, through the glove port to atmosphere. Under these conditions the velocity of the air flowing into the glove box through a 6 inch diameter port has been measured as 35 ft/min. It has been recommended however that under breach conditions the air flow into the glove box through the breach should have a minimum velocity of lOOft/min and that the main extract duct depression should not exceed -6 inches WG.

The arrangement of the invention is such that manipulation of a valve is not normally required. Under normal circumstances the supply pressure to the main inlet of the vortex amplifier (being that of the glove box) is slightly less than the pressure at the control inlet (being that ofthe atmosphere outside the glove box) whilst the vortex amplifier outlet pressure is less than both the supply pressure and the control pressure. With these conditions a control flow is induced through the control inlet of the vortex amplifier and this throttles the flow from the glove box. If a breach in containment occurs due to a glove becoming detached from a glove port then the supply pressure to the amplifier becomes effectively the same as the control pressure which remains at that of the atmosphere. The outlet pressure also remains unchanged. With these conditions there is little or no control How and therefore the flow from the glove box passes through the amplifier with minimum losses. The increase in total flow rate is considerable by as much as a factor of six, for example and is obtained automatically as the control pressure changes.

In the case of a small leak somewhere on the glove box, there will be a tendency to reduce the box depression. However this reduction means that less control flow is being induced into the amplifier and therefore more main flow is allowed. The increase in main flow can compensate for the small leak and therefore the glove box containment can be maintained although at a slightly smaller depression than normal. With a conventional system even very small leaks destro the glove box depression almost entirely.

The application of the invention is not restricted to glove boxes. It provides an alternative to fume hoods in the chemical and pharmaceutical industries and a means of carrying out operations in the electronic industry. for example in transistor manufacture and assembly. The containment may he a relatively large room and the cause of a breach" the opening of a door in the room. Also the containment may provide means for carrying out clean operations segregated from a dirty atmosphere as well as the reverse procedure so far described. For example a clean chamber may be slightly pressurised to prevent the entry ofdust and its entrance may be guarded by an air lock with two doors one leading into the chamber and one to atmosphere. It is envisaged that this air lock may serve as a containment in accordance with the invention. being provided with an extract system incorporating a vortex amplifier as already described and maintained at a lower pressure than the clean chamber and at the same or a lower pressure than the outside atmosphere to which the control inlet of the amplifier is connected. Thus on opening the door between the air lock and the clean chamber an increase in the supply flow through the amplifier can be arranged to follow either because the increase in pressure in the air lock brings the air lock pressure closer to or above the control pressure or because the opening of the door actuates means cutting off the control flow. Opening of the door between the air lock and atmosphere can be arranged to produce a similar effect.

DESCRIPTION OF THE DRAWING The invention will now be further described with reference to the accompanying drawing which is a line diagram.

DESCRIPTION OF THE PREFERRED EMBODIMENT The drawing shows part of a glove box I having an air inlet 2 fitted with a filter 3. An outlet 4 fitted with a filter 5 is connected as the main flow inlet to a vortex amplifier 6 having a control flow inlet 7 fitted with a filter 8 and an outlet 9 to a duct 10 provided with an extractor fan (not shown). The drawing also shows a modification of the arrangement in which a bypass line 11 fitted with a filter l2 and variable restrictor 13 connects the interior of the glove box I with the duct I0. In the modified arrangement the only flow through the amplifier 6 under normal conditions is from atmosphere through the control inlet 7. This flow blocks off completely main amplifier flow from the glove box 1. The extract air from the glove box goes instead through the filter 12 direct to the main extract duct. If a breach occurs the control flow is reduced or removed completely. Flow then takes place across the filter 5 and through the amplifier to the main duct. This system uses the vortex amplifier 6 as a standby safety circuit whereby the filter 5 can remain in an "as new" condition until breach conditions occur.

We claim:

1. In a containment segregating a space from its surrounding atmosphere and provided with an extract system for the atmosphere of the containment the improvement of including in the system a vortex amplifier venting into the system at a point where the system Ill fluid flow connection including a variable flow restrictor is provided between the containment and the extract systemr bypassing the vortex amplifier.

3. The improvement of claim 1 wherein the containment is a glove box.

4. The improvement of claim 2 wherein the containment is a glove box. 

1. In a containment segregating a space from its surrounding atmosphere and provided with an extract system for the atmosphere of the containment the improvement of including in the system a vortex amplifier venting into the system at a point where the system pressure is lower than that of the containment when the extract system is operating, the vortex amplifier also having its main inlet in fluid flow connection with the containment and a control inlet in fluid flow connection with the atmosPhere outside the containment arranged to provide a control flow to throttle fluid flow through the vortex amplifier main inlet.
 2. The improvement of claim 1 wherein a further fluid flow connection including a variable flow restrictor is provided between the containment and the extract system, bypassing the vortex amplifier.
 3. The improvement of claim 1 wherein the containment is a glove box.
 4. The improvement of claim 2 wherein the containment is a glove box. 